arnyk the 339A has a stepped level attenuator. The level adjust pot is internal between stages. It's not possible to connect it in an isolated way.
My statement about pot distortion was perhaps too general and I don't disagree with you that pots can exhibit very low distortion but in the context of ultra low distortion oscillators and distortion analyzers they can. And maybe the difference is not significant in your option. But it to some.
I'm not going to fill this thread up on the subject of pot distortion because it's covered in other threads and not really what this thread is about.
Thanks Jan,
I like this idea.
I'll put part 2 together.
On tuning an SVO with stepped attenuators it's a more complicated subject.
We'll see how it goes.
Dave how did your distortion analyzer comparison article go.
Did you get it published?
Thanks Rob for catching that.
That was MS spell check thinking it knows better. Everything was cut and paste.
Not a problem. Any distortion it creates shows up at all points downstream of it, which includes the output terminals of the internal oscillator.
No perhaps. It was hyper general. No actual context. Exceptions were not even just alluded to.
It is the sort of statement that anybody who knows anything about critical thinking is obliged to question simply because of how poorly it was written.
But they still don't have to, and your statement was perfectly general. No context was stated, and the context you responded it was not just measurement equipment.
If taken at face value it was said that all possible applications of all possible potentiometers will pick up excessive distortion (whatever that is!).
Reality would appear to be that you really don't know. And you don't seem to want to uncover any evidence that does not agree with you. I see the possibility that yet another "audiophile truth" was being shared.
Of course it is significant "to some" whoever they are. This is yet another vague claim that sheds zero actual light on what the truth is.
This is known in the trade as dissembling. You have thus far provided zero evidence or real-world quantification of the purported "audiophile truth" that you appear to have been baselessly mouthing. This is in spite of the fact that have a great test case ready made and sitting on your bench.
This is called compounding one baseless speculation with yet another.
You apparently provide can't even be bothered to provide a thread name.
You really need to read Fieniman's Carg Cult Science and see yourself in there: Cargo Cult Science
There, I even did you the courtesy of providing both article title and a link to a public source for it! Something you avoided doing for me. Of course, the article really is on my side of the discussion as are vitually all articles about good Science.
Truth be known, I have been anticipation this post in detail for days. Thanks for confirming your position.
Last edited:
Arny - Please clarify for me as I don't understand your point.
It was proven that when changing the HP339a level
pot to a lower distortion pot, the oscillator's output had lower distortion.
I don't see an issue with a guy or gal generalizing, it's how we survived as
a species.
If you are interested you are more than welcome to read through the
Low Distortion Oscillator thread to see the data. Starting at post 600
is a good place to start.
Save up and buy one if you'd like to join us an help make it better.
Think you can?
Also, just do a search of HP339a in google limit the site to DIYAudio if you want only this site.
It would be nice if you would contribute something instead of criticizing and trying to make someone
who's contributed alot here. No body is perfect ya know. I'm not calling you a troll but sometimes
I wonder.
Cheers,
Sync
It was proven that when changing the HP339a level
pot to a lower distortion pot, the oscillator's output had lower distortion.
I don't see an issue with a guy or gal generalizing, it's how we survived as
a species.
If you are interested you are more than welcome to read through the
Low Distortion Oscillator thread to see the data. Starting at post 600
is a good place to start.
Save up and buy one if you'd like to join us an help make it better.
Think you can?
Also, just do a search of HP339a in google limit the site to DIYAudio if you want only this site.
It would be nice if you would contribute something instead of criticizing and trying to make someone
who's contributed alot here. No body is perfect ya know. I'm not calling you a troll but sometimes
I wonder.
Cheers,
Sync
Last edited:
David, thanks for remembering. Yes, I just read / edited the formatted proof last week. It will be in the AudioXpress April issue. Do you get AX? If you do not, let me know. I gained quite a bit of knowledge while working on the article and also gained some reassurance about information I already obtained. I'm hoping it helps other readers on my level (enthusiastic hobbyist).
In all seriousness, you do have a great article in the works. IMO, that is the type of article that helps fuel interest in building. You provided excellent theory and the build is not very difficult (regarding circuit boards, power supplies, etc.). The reader can build and customize what you have provided. I already have two attenuators from HP. After reading your post, I started thinking of building one that suits my needs where my HPs fall short.
All the best!
Dave
Hi Arny,
This isn't the place for these types of arguments. In fact, a new control pot does reduce the distortion, and this has been proved empirically.
Please, before going any further down this path, read the prerequisite material that sync suggested for you. Quite a lot of work has been done on this and related subjects on the HP 339A.
This is a technical thread, getting picky about the language isn't helpful to anyone. David has been clear so far, and it is the technical information that is important.
Now, if you wish to join that conversation, please purchase an HP 339A distortion measurement set, perform some of the described work and see where that leads. Once that has been done you are qualified to comment honestly on your personal findings. Failing that, you are more than welcome to read along and learn with the rest of us. We don't need this thread dragged off topic without good reason.
-Chris
This isn't the place for these types of arguments. In fact, a new control pot does reduce the distortion, and this has been proved empirically.
Please, before going any further down this path, read the prerequisite material that sync suggested for you. Quite a lot of work has been done on this and related subjects on the HP 339A.
This is a technical thread, getting picky about the language isn't helpful to anyone. David has been clear so far, and it is the technical information that is important.
Now, if you wish to join that conversation, please purchase an HP 339A distortion measurement set, perform some of the described work and see where that leads. Once that has been done you are qualified to comment honestly on your personal findings. Failing that, you are more than welcome to read along and learn with the rest of us. We don't need this thread dragged off topic without good reason.
-Chris
The work on the 339A is very thorough and detailed. No one wants or needs to repeat any of it for late comers like arnyk. I also replaced that pot and found the thd lower. from that we evolved to needing even lower distortion gen source (pref of variable freq). And also analyzer upgrades of the 339 and ShibaSoku.
The work has spun into other separate discussions. SG has entered the low distortion gen design also.
Quite a lot of work spread over time and places here at DIYAudio. The attitude expressed by arnyk is very arrogant and not worthy of further comment.
My own interest was just to be able to measure the thd of my headphone amp. The 339A could not do it... even after mods. Plus many other sources were bought and modified..... such as, Krone-Hite models and Victor's. Then to the many ADC sound-card types were modified. Then various notch filters were bought/modified or designed to extend the distortion measurement range.
Eventually, to get to where I needed to be -- lead me to buy a ShibaSoku 725D and then a full blown A-P 2722 (with IM option etc) and several Panasonic industrial analyzers. I am still not reading the amp distortion at the best analyzers floor and still need better osc/gen. David and Samuel, R. Moore and Demian and others have been supportive and doing some original work at Ultra low distortion audio T&M.
Else where, I have encouraged ultra low distortion, high power, ultra fast CFA power amps and that has born fruit also.... and now I am equipped to measure them. Phew! Tens of thousands of dollars later and years of effort. Instead of hassling these guys, they should all be thanked... and Bob C. of course.
THx-RNMarsh
Last edited:
Hi Dave,
Congratulations! I'm really looking forward to reading the article.
Cheers,
Bob
Well, we all have our bad days. Let Arny have his without taking it too seriously. You people have made me looking deeper that I intended in the art of silence 🙂. Yes, indeed and it has cost me a handsome pile of money as I have to try and learn from your posts 😀. One day I might create my own oscillator, notch filter, 100dB preamp and only God nows how much you people are going to cost me in the future 🙂.
So lets move on and forget the bad days.
Regards
So lets move on and forget the bad days.
Regards